Dakota Digital CMX Material Calibration, Known Velocity, Using a Known Material Velocity

CMX High Performance Material & Coating Thickness Gauge

7)Press the OK key to complete the probe zero function, or ESC key to cancel the probe zero function.

8)Remove the transducer from the probe zero disk, and proceed to the calibration section.

Note: The value that is displayed will change depending on the current velocity

setting in the CMX. Disregard the number that is displayed. It is not

important. What is important is accurately performing the steps outlined above

to insure reliability of the probe zero calculation.

6.3 Material Calibration

In order for the CMX to make accurate measurements, it must be set to the correct sound velocity of the material being measured. Different types of materials have different inherent sound velocities. For example, the velocity of sound through steel is about 0.233 inches per microsecond, versus that of aluminum, which is about 0.248 inches per microsecond. If the gauge is not set to the correct sound velocity, all of the measurements the gauge makes will be erroneous by some fixed percentage.

The One Point calibration is the simplest and most commonly used calibration method - optimizing linearity over large ranges. The Two Point calibration allows for greater accuracy over small ranges by calculating the probe zero and velocity. The CMX provides four simple methods for setting the sound-velocity outlined below:

Known Velocity

If the material velocity is known, the user may wish to simply enter the velocity number into the CMX, rather than have the CMX calculate the velocity value using a known thickness on a material sample. The steps for entering the velocity are outlined below:

Using a Known Material Velocity

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